Load supporting roller assemblies

ABSTRACT

A roller assembly for supporting sliding doors on a track or rail comprises a plurality of short rollers (10) which are confined to run around an oval track (9a) formed in a two part housing (7). Some of the rollers (10) are engageable with the track through an elongate slot (13) in the base of the housing (7) so that load is distributed over several rollers. The housing (7) is mounted for adjustment in a carrier (5) which can be mounted on a door. The adjustment permits variations in height or levels to be accommodated.

BACKGROUND OF THE INVENTION

1. Field of the Invention:

This invention concerns improvements in or relating to load supportingroller assemblies of the kind that are used for engagement with a trackor rail to permit movement of a heavy element carrying the rollerrelative to the track. In particular, but not exclusively, thisinvention has application for supporting a door or window for slidingmovement along a rail.

2. Description of Prior Art:

It is already known to provide roller assemblies that are like wheelshaving some form of axle for mounting the wheel for rotation. It is alsoknown to provide wheels having specially shaped rims, or even tyres forlocation on a rail or track. It is also known to provide rollerassemblies made of various materials to resist wear and to reducefriction. However, the known type of roller assembly usually suffersfrom one distinct disadvantage when used for supporting a heavy element,and this is that there is only a very small area of contact with therail or track through which the load and pressure is exerted. This loadand pressure means that wear and distortion occurs both in the rollerand the track, and even the provision of a tyre or special track or railcannot obviate this in many cases without making the eventual assemblytoo cumbersome, or too expensive, or even so complex that repair orreplacement is impractical.

Summary of the Invention

It is an object of this invention to provide a roller assembly of animproved construction to avoid the foregoing disadvantages.

According to this invention we provide a roller assembly adapted formounting on an element for movement on a track or rail, the rollerassembly comprising a housing defining a continuous path in which aplurality of short rollers are located for rolling movement along andaround said path, the housing having an elongate slot or groove openingto a substantially linear portion of said path whereby a plurality ofthe rolling contact faces of the short rollers are presented forengagement with the track or rail.

As will be understood, the provision of a plurality of rolling contactfaces in the roller assembly according to this invention permits theload/pressure to be distributed through a larger contact or bearing areathan with a single wheel or roller.

Preferably, the roller housing defines a path which is oval and alongwhich the short rollers move in use. The short rollers are convenientlyin the form of cylindrical bodies with each of their opposed endslocated in the housing so that the central portion of each short rollersprovides the rolling contact face exposed through the slot or groove inthe housing.

Conveniently, the housing is formed in two similar opposite-handedparts, each with an oval-shaped groove so that when the two parts areassembled together, the grooves define said path. The number and size ofshort rollers may be varied and may depend on criteria of load, bearingcontact and the rail or track.

In a rail or track of the upstanding type, for example with a rib orbead for engagement with the rolling contact faces, the opposed sides ofthe slot or groove in the housing of the invented roller assembly mayprovide abutment or guide faces to locate the roller assembly on therail or track.

Preferably, the housing and the short rollers may be made of a lowfriction material, for example an acetal resin. The type of material orresin may be chosen in accordance with the physical properties required,but other materials may be used as compatible with the material used forthe truck or rail. Acetal resins are particularly suitable for use withaluminium alloys as commonly used in tracks or rails for sliding doorsor windows.

Another problem arising with roller assemblies used for sliding doors orwindows is providing for adjustment to accommodate differences in theheight of the aperture or rail spacing and to adjust the door or windowduring fitting or service. The housing of the invented roller assemblyis specially mounted in a carrier which is adapted to allow both fittingof the roller assembly, and to allow adjustment of the housing relativeto the carrier.

In a preferred arrangement, the carrier includes at least one faceengaged by the housing and inclined relative to the linear portion ofsaid path of the short rollers, the housing being mounted for adjustingmovement on said inclined face to vary the distance between the extentof said linear portion so as to enable the member carried by theinvented roller assembly to be raised or lowered relative to the trackor rail.

Such adjustment may be achieved by a simple screw or stud arranged tourge or move the housing relative to the carrier along said inclinedface. Preferably, there are two such inclined faces which locate thehousing on the carrier. An abutment or stop may be provided to restrictmovement of the housing.

Further features of this invention will be explained with reference toan exemplary embodiment shown in the accompanying drawings which depicta roller assembly according to this invention as applied to an elementcomprising a patio door.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts one corner of a patio door (partly sectioned) mounted bya roller assembly for sliding movement on a track;

FIG. 2 is a view similar to that of FIG. 1, but depicting the rollerassembly in an adjusted position to raise or lift the patio doorrelative to the track;

FIG. 3 is a partly sectioned detail view of the roller assembly; and

FIG. 4 is an exploded isometric view of the roller assembly.

With reference to this embodiment of the invention, the drawings ofFIGS. 1 and 2 depict a conventional upstanding track or rail 1 set downfor carrying a patio door having a metal frame comprising a stile 2 anda lower cross member 3. The frame would be glazed, wholly or partly, inknown manner, and the lower cross-member 3 would include a section ofinverted channel shape inside which the roller assembly 4 would beconcealed. Furthermore, the stile 2 would be of hollow section. Usually,the metal frame comprises extruded aluminium sections.

The roller assembly 4 comprises a carrier 5 adapted by means ofcountersunk threaded bores 25 for fixing to the frame members of thedoor by fixing screws 26 and 27. Any suitable fixings may be provideddepending on the design and construction of the door.

The carrier 5 is generally of rectangular shape in top plan view but hastwo opposed similar side portions 6 which are spaced apart and define achannel shaped recess therebetween in which a housing 7 is received. Thecarrier 5 is preferably metal, and may comprise a casting, such as adie-casting, or it may be a fabrication.

The housing 7 is formed of two similar opposite-handed parts, 7a and 7bwhich are held together by a central bolt and nut 8. Each housing part7a,7b, includes an oval shaped groove 9a, the section of the groovebeing channel-shaped to receive the ends of a plurality of shortcylindrical rollers 10. As will be appreciated, especially as shown inFIGS. 3 and 4, the grooves 9a define a path in which the rollers 10 areconfined when the housing parts 7a,7b are connected together.

The rollers 10 are arranged with sufficient clearance to permit theirrolling movement around the path. The housing parts 7a and 7b and therollers 10 may be of a low friction plastics material such as acetalresin.

For convenience in assembly, and for locating the housing parts 7a,7btogether, lugs 11 may be provided on one housing part to be received incomplementary holes in the other housing part, or separate pins may beprovided. Additionally, the inside face of the carrier if formed with ashort longitudinal rib (not shown) which seats in a longitudinal slotformed in the assembled housing 7 by the rebates 12a,12b, extending onthe mating faces of the housing parts 7a and 7b.

The housing parts 7a,7b also have rebates 13a extending along theirrespective lower edges which open to the respective grooves 9a. In theassembled housing, these rebates 13a form an elongate slot 13 throughwhich a plurality of the rollers 10 are presented for rolling engagementwith the head of the rail 1. The extent of these rollers 10 presentedfor rolling engagement is substantially linear and each roller 10provides a bearing face through which loads may be transmitted. Thisachieves a spreading of the total load along a length of the rail 1 andhigh point loading is avoided.

Additionally, the opposed side faces of the slot 13 serve to extend onrespective sides of the head of the rail, and this assists in locatingand guiding the roller assembly carrying the door along the length ofthe rail during sliding movement.

According to a further feature of this roller assembly, the housing 7carrying the short rollers 10 may be adjusted relative to the carrier 5to raise or lower a sliding door relative to the rail 1. This adjustmentmay be required during fitting, removal, or on settlement or wear ofparts.

For this adjustment, each side portion 6 of the carrier 5 is providedwith an inclined face 14 against which a similar respective inclinedface 15 on each side of the housing is slidably engaged and located. Theend face 16 of the housing assembly is provided with small thrust plate17 located in an undercut. This plate 17 is arranged to be engaged by anadjuster screw 18 in threaded engagement with the end wall 19 of thecarrier. On rotation of the head of the adjuster screw 18 through aclearance opening provided in the frame stile 2, the housing 7 can bemoved along the inclined face so as to vary the position of the housingwith respect to the carrier 5. Two extremes of adjustment are shown inFIGS. 1 and 2.

To hold the roller assembly together, and to limit the adjustment, astop plate 21 is mounted in an undercut rebate 22 formed in the end faceof the carrier 5 opposed to the thrust plate 17. The stop plate 21 isarranged to provide an abutment for engagement by two lugs 23a,23bformed respectively on the housing parts 7a,7b. These lugs 23a,23b areeach arranged so as to extend parallel to the inclined face 14 to assistin guiding and location, and to complement supplementary inclined slotswith guide faces 24 provided in the side portions 6 of the carrier.

It will be understood that the range of adjustment can be varied bychanging the dimensions of the carrier and the housing, and a wide rangeof load bearing capacities can also be accommodated by changing thelength of the roller path, type of material used and othercharacteristics.

Tests have been carried out on a roller assembly in accordance with theforegoing embodiment in which the housing and roller were of acetalresin. The rollers were made from polyacetal rod and of about 8 mmdiameter. A pair of roller assemblies were mounted on a door having aweight of 113.6 Kilogrammes and the door was arranged to be movedbackwards and forwards on a track length of 1.22 meters. Each cyclerepresenting 2.44 meters of rolling engagement for each roller assemblyand the cycles per hour were rated at 420. After 30,000 cycles and aperiod of rest or static load corresponding to 200 hours, the rollerassemblies were inspected, and no visible signs of wear of the rollersor the housing parts forming the path for the roller movement wasdiscernible. Accordingly, an extra load was applied to the door, thisbeing 45.5 Kilogrammes, and a further 10,000 cycles were completed with50 hours of rest under the static load. Again, after inspection, nodiscernible sign of wear or damage was found, and both roller assemblieswere fit for further service. The tests can be put into usageperspective by noting that 40,000 cycles corresponds to 4 openings andclosings of a door each day for a period of 27 years. It is alsoimportant to note that the tests included static load periods duringwhich local distortion or stresses could arise, but these were notevident because the load is distributed over a plurality of rollers inengagement with the track.

Furthermore, although there are manufacturing and assembly advantages ofusing short rollers of right-cylindrical configuration, otherconfigurations could be used. For instance, the rollers could be shapedto complement the configuration of the head of the rail; the ends of therollers could be stepped, or the rollers could be assemblies of sleevesor tubes on a carrier pin.

It will also be appreciated that the roller assembly according to thisinvention can easily be dismantled or replaced, and servicing likelubrication is not required. Although the housing is preferably made ofa low friction material, it could be made of a metal, such as aluminiumor zinc alloy, selected to have suitable compatible wear and frictioncharacteristics for use with the rollers.

It is also envisaged that the construction of the carrier could bevaried, in particular, to provide an open-sided box-like carrier whichencloses the housing assembly, and a simple plate to close the side andhold the assembly together. In such an arrangement the box-like carrierwould provide the inclined face(s) and complementary grooves or recesseswould be provided in both the open-sided part and the side plate.

What we claim is:
 1. A roller assembly for mounting on an element forsliding movement on a rail, said assembly comprising:a roller housinghaving two complementary parts, each said part being formed with arespective complementary groove of oval configuration defining an ovalcontinuous path; a plurality of short rollers of right-cylindricalconfiguration located in said housing for rolling movement along andaround said path with their opposed ends each being located in saidrespective complementary groove; and an elongate slot in said housingopening to a substantially linear portion of said path whereby aplurality of rolling contact faces being central portions of said shortrollers are presented for rolling engagement with said rail in use.
 2. Aroller assembly according to claim 1 wherein said short rollers areformed of acetal resin and said housing is mounted in a carrier, saidhousing and said carrier each having respective faces inclined relativeto said linear portion of said path, said carrier comprising a metalbody having two inclined faces each for guiding and locatingcomplementary formations on said housing, and means on said carrier foracting between said carrier and said housing for adjusting displacementof said respective inclined faces whereby the vertical position of saidhousing relative to said carrier is varied between two extreme positionsof adjustment limited by means of said carrier.